A pesticide used prior to the early 1980s and found in milk at that time may be associated with signs of Parkinson’s disease in the brain, according to a study published in the December 9, 2015, online issue of Neurology®, the medical journal of the American Academy of Neurology. “The link between dairy products and Parkinson’s disease has been found in other studies,” said study author R. D. Abbott, PhD, with the Shiga University of Medical Science in Otsu, Japan. “Our study looked specifically at milk and the signs of Parkinson’s in the brain.”

Parkinson’s Disease (PD) is a chronic progressive disorder of the nervous system that affects the person’s ability to move. According to the CDC, every 3 out of 100,000 people in the US died from this disease in the 1980s, in the early 2000s that number doubled. A new study published in the journal Neurology on Dec. 9 shows a possible link to this increase — a pesticide (heptachlor) that was found in milk in the early 1980s.

The researchers from Shiga University of Medical Science in Japan noticed this connection when they studied Japanese-American men in Hawaii – the state where this pesticide was used frequently, reportedThe Huffington Post. Men who drank two or more glasses of milk per day (16 oz) at the start of the study had 40% fewer brain cells in the substantia nigra (associated with movement) part of the brain 30 years later (comparing to men who drank less than two cups of milk per day).

The researchers also discovered that 90% of men who drank the milk had residues of the pesticide (heptachlor epoxide) in their brains. Only 63% of men who did not drink milk had these residues.

According to the Medical Encyclopedia from the U.S. National Library of Medicine, PD slowly develops as cells are destroyed in parts of the brain, especially in the substantia nigra. Because PD is a slow progressive disease, visible symptoms of it can take decades to appear, meaning this disease may still be manifesting itself in people who have been exposed to heptachlor and other pesticides.

Was This Pesticide Prevalent in Hawaii because of the Pineapple Industry?

The pesticide was used for insect control by the pineapple industry in Hawaii in 1980s, and high levels of it ended up in the milk supply because the cows were fed parts of the pineapple debris, according toTime. It was banned in commercial agriculture in 1988, according to the U.S. Environmental Protection Agency. Timemagazine reported that even though banned, the pesticide may remain in water and soil for many years.

How the Study Was Conducted:

The study, titled “Midlife milk consumption andsubstantianigra neuron density at death,” looked at 449 Japanese-American men for at least 30 years until their deaths. After they died, the researched performed autopsies, studies the cells in thesubstantianigra and the residues of the pesticide in the brains.

Is there a legitimate Milk-Parkinson’s connection?

Even though it is known fact that a lot of milk in 1980s contained the pesticide, and a high amount of it, the milk that the men drank was not tested, so there is no way to show a cause-and-effect relationship between PD and this pesticide. However, the study shows an association between the two.

The study’s author Robert D. Abbott said that the researchers see “no other explanation for how heptachlor epoxide found its way into the brains of men who consumed milk.”

“We don’t have all the data yet, but we are close to finding the smoking gun here. It’s not complete, but it’s very suspicious,” he said.

Can pesticides cause PD? The current understating in medicine is that PD is caused by a combination of genes and environmental factors, diet being one of them.

“Your genes load the gun and the environment pulls the trigger,” states the National Parkinson Foundation website.

Abbott said that people should try to avoid consuming food that contains pesticides in general.

This Pesticide is Still Used Today!

Heptachlor/ heptachlor epoxide was banned in 1988 for use in agriculture and for insect-control in homes but is still used for fire ant control in power transformers, according to the CDC.

Unfortunately, heptachlor is not the only pesticide that may come with an inherent risk for Parkinson’s Disease. As many as 11 commonly used pesticides have been linked to PD, including glyphosate, the active ingredient in Monsanto’s Roundup.

And if this study is any indication it may be wise to avoid non-organic milk, since today’s cows are known to feast on genetically engineered corn that has been doused with glyphosate, instead of their natural diet of nutrient-rich grasses.